This application is based on and incorporates herein by reference Japanese Patent Application No. 2002-171281 filed on Jun. 12, 2002.
1. Field of the Invention
The present invention generally relates to an ignition coil device for an engine of, for example, an automobile and more specifically to an ignition coil assembly that includes a plurality of ignition coils, which are connected to corresponding spark plugs securely installed in plug holes of the engine.
2. Description of Related Art
For example, Japanese Unexamined Patent Publication No. 9-250437 discloses an integrated connector block, in which connectors for supplying electricity to corresponding ignition coils are integrated. The integrated connector block includes a connector block main body, which is formed as an elongated body made of a resin material. Coil connectors are integrally formed in a lower surface of the connector block main body. Each ignition coil, which is secured to a corresponding spark plug installed in an engine, is installed to and is thus engaged with a corresponding one of the coil connectors in an axial direction of the corresponding ignition coil, i.e., in an axial direction of the corresponding spark plug.
Furthermore, in order to allow installation of the ignition coils to the plug holes of the engine in a single step, an ignition coil assembly, which includes a plurality of ignition coils arranged at predetermined intervals, has been proposed. For example, as shown in FIG. 12, one such ignition coil assembly 51 includes a base cover 53 and a top cover 54. The base cover 53 is made of a resin material and has a plurality of receiving through holes 53a, each of which receives a main body 52b of a corresponding one of a plurality of ignition coils 52. The ignition coils 52 are arranged at corresponding positions, which correspond to positions of plug holes 131 of an engine 130. The top cover 54 is connected to the base cover 53 in such a manner that the top cover 54 covers a top surface of the base cover 53. The top cover 54 includes a plurality of protrusions 54a. Each protrusion 54a presses a head 52a of the corresponding ignition coil 52. The ignition coil assembly 51 is installed to a top surface of the engine 130 in such a manner that each ignition coil 52 is axially installed into a corresponding one of the plug holes 131, and fastening bolts 55 are inserted through corresponding through holes 53d, 54d of the base and top covers 53, 54, which are provided at longitudinal ends and the center of the base and top covers 53, 54. Then, the fastening bolts 55 are threadably engaged with corresponding threaded screw holes 133 of the engine 130. In this way, the ignition coil assembly 51 is secured to the engine 130.
However, in the case of the previously proposed ignition coil assembly 51, when one or some of the ignition coils 52 need to be replaced after the installation of the ignition coil assembly 51 into the engine 130, it requires tedious and time consuming reinstallation operation of the ignition coil assembly 51 after replacement of the ignition coils 52. That is, in the ignition coil assembly 51, the base cover 53 and the top cover 54 are integrally secured to the engine 130 by the fastening bolts 55. Thus, when the fastening bolts 55 are removed, both the top cover 54 and the base cover 53 are released from the engine 130, and thus the base cover 53 tends to be misaligned relative to the engine 130 (see positional deviation of the base cover 53 in FIG. 13). At the time of reinstallation of the ignition coil assembly 51 into the engine 130, the receiving through holes 53a of the base cover 53 need to be aligned with the plug holes 131 once again, requiring extra time for the reinstallation.
The present invention addresses the above disadvantage. Thus, it is an objective of the present invention to provide an ignition coil assembly, which allows removable of only a top part of the assembly to facilitate replacement of one or more ignition coils.
To achieve the objective of the present invention, there is provided an ignition coil assembly for an engine. The engine includes a plurality of plug holes, each of which receives a corresponding one of a plurality of spark plugs. The ignition coil assembly includes a plurality of ignition coils, a base cover, a top cover, a connecting member and a fastening member. The ignition coils are arranged to be electrically connected to the spark plugs, respectively. The base cover supports the ignition coils at corresponding positions, which correspond to positions of the plug holes, respectively. The top cover covers a top surface of the base cover. The connecting member connects between the top cover and the base cover. The fastening member secures only the base cover to the engine.